Such glow discharges may be employed, for example, in order to obtain continuous lasers of high power density. For example, such a gas-dynamic CO-laser is known, wherein the gas travelling through the glow path between anode and cathode is subsequently cooled to very low temperatures, whereby the inversion necessary for a laser effect is obtained. In order to increase the output density of such lasers; it is a condition that the power density in the glow discharge is as high as possible for exciting the gas.
Heretofore, a tubular anode was used in similar glow discharges burning in gas streams, wherein the gas was introduced into the discharge tube proper either through the anode tube itself or through radial slots in front of the anode tube. By means of such arrangements power densities of up to approximately 50 W/cm.sup.3 could be obtained. The literature cited below represents the present state of the art.
I. w. rich, R. C. Bergmann, J. A. Lordi, Electrically excited, supersonic flow carbon monoxide laser, AIAA J., Vol. 13. No. 1, Jan. 1975. PA1 H. brunet, M. Mabru, Improved performance of an electric-discharge N.sub.2 -CO mixing laser, J. of Appl. Physics, Vol. 46, No. 7, July 1975. PA1 W. l. nighan, Stability of high power molecular laser discharges, United technologies Res. Center, Rep. 75-19. PA1 J. w. daiber, H. M. Thompson, Th. J. Falk, The efficiency of CO vibrational excitation in a self-sustained CW glow discharge, IEEE J. of quantum electronics, Vol. 12, No. 11, 1976.
However, it has been found in the operation of a glow discharge by the methods known heretofore that limits are set to an increase of the power density by the fact that the glow discharge changes into an arc discharge. This change-over expresses itself first in a number of filamentary arc discharges which start from certain locations of the anode. In order to prevent such local arc discharges as far as possible, for example the width of a radial inlet gap for the flowing gas has been maintained with the highest precision heretofore (see the paper by Daiber et.al. referred to above, in the periodical IEEE J. of quantum electronics, of Nov. 11, 1976). However, even these measures could not lead to an increase of the power density exceeding the value stated above.